The Unified Socialist League (Japanese: Toitsu shakaishugi domei, abbreviated Toshado) was a pro-Soviet communist organization in Japan, founded on May 3, 1962. The Unified Socialist League was led by Kasuga Shojiro, formerly a leading figure in the Japanese Communist Party. Makoto Omori was the general secretary of the organization. The organization emerged from a split from the Preparatory Communission for a Socialist Reform Movement (a.k.a. the 'Socialist Renovation' group). The membership of the Unified Socialist League (numbering around 600) was dominated by students, and the organization had a student wing called the Socialist Student Front.
The Unified Socialist League published a monthly journal, Kozo Kaikaku ('Structural Reform'). It had a circulation of around 2,200. Kozo Kaikaku was published between May 1962 and December 1963. In May 1964 the Unified Socialist League launched a new publication, Heiwa to Shakaishugi.
The Unified Socialist League repeatedly attacked the Communist Party of Japan, arguing that the party lacked internal democracy and that it was subservient to Chinese interests. The Unified Socialist League did not put forth candidates in national elections.